/*

 * HEIF codec.

 * Copyright (c) 2022 Dirk Farin <dirk.farin@gmail.com>

 *

 * This file is part of libheif.

 *

 * libheif is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation, either version 3 of

 * the License, or (at your option) any later version.

 *

 * libheif is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with libheif.  If not, see <http://www.gnu.org/licenses/>.

 */

#include "init.h"

#include "libheif/heif.h"

#include "error.h"

#include "plugin_registry.h"

#include "common_utils.h"

#include "color-conversion/colorconversion.h"

#if ENABLE_MULTITHREADING_SUPPORT

#include <mutex>

#endif

#if defined(_WIN32)

#include "plugins_windows.h"

#else

#include "plugins_unix.h"

#endif

void heif_unload_all_plugins();

#if ENABLE_PLUGIN_LOADING

void heif_unregister_encoder_plugin(const heif_encoder_plugin* plugin);

std::vector<std::string> get_plugin_paths()

{

  std::vector<std::string> plugin_paths;

#if defined(_WIN32)

  plugin_paths = get_plugin_directories_from_environment_variable_windows();

#else

  plugin_paths = get_plugin_directories_from_environment_variable_unix();

#endif

  if (plugin_paths.empty()) {

    plugin_paths.push_back(LIBHEIF_PLUGIN_DIRECTORY);

  }

  return plugin_paths;

}

std::vector<std::string> list_all_potential_plugins_in_directory(const char* directory)

{

#if defined(_WIN32)

  return list_all_potential_plugins_in_directory_windows(directory);

#else

  return list_all_potential_plugins_in_directory_unix(directory);

#endif

}

#else

std::vector<std::string> get_plugin_paths()

{

  return {};

}

#endif

static int heif_library_initialization_count = 0;

static bool default_plugins_registered = true; // because they are implicitly registered at startup

#if ENABLE_MULTITHREADING_SUPPORT

static std::recursive_mutex& heif_init_mutex()

{

  static std::recursive_mutex init_mutex;

  return init_mutex;

}

#endif

void load_plugins_if_not_initialized_yet()

{

  if (heif_library_initialization_count == 0) {

    heif_init(nullptr);

  }

}

heif_error heif_init(heif_init_params*)

{

#if ENABLE_MULTITHREADING_SUPPORT

  std::lock_guard<std::recursive_mutex> lock(heif_init_mutex());

#endif

  if (heif_library_initialization_count == 0) {

    ColorConversionPipeline::init_ops();

    // --- initialize builtin plugins

    if (!default_plugins_registered) {

      register_default_plugins();

    }

#if ENABLE_PLUGIN_LOADING

    struct heif_error err{};

    std::vector<std::string> plugin_paths = get_plugin_paths();

    for (const auto& dir : plugin_paths) {

      err = heif_load_plugins(dir.c_str(), nullptr, nullptr, 0);

      if (err.code != 0) {

        return err;

      }

    }

#endif

  }

  // Note: it is important that we increase the counter AFTER initialization such that

  // 'load_plugins_if_not_initialized_yet()' can check this without having to lock the mutex.

  heif_library_initialization_count++;

  return {heif_error_Ok, heif_suberror_Unspecified, Error::kSuccess};

}

void heif_deinit()

{

#if ENABLE_MULTITHREADING_SUPPORT

  std::lock_guard<std::recursive_mutex> lock(heif_init_mutex());

#endif

  if (heif_library_initialization_count == 0) {

    // This case should never happen (heif_deinit() is called more often than heif_init()).

    return;

  }

  if (heif_library_initialization_count == 1) {

    heif_unregister_decoder_plugins();

    heif_unregister_encoder_plugins();

    default_plugins_registered = false;

    heif_unload_all_plugins();

    ColorConversionPipeline::release_ops();

  }

  // Note: contrary to heif_init() I think it does not matter whether we decrease the counter before or after deinitialization.

  // If the client application calls heif_deinit() in parallel to some other libheif function, it is really broken.

  heif_library_initialization_count--;

}

// This could be inside ENABLE_PLUGIN_LOADING, but the "include-what-you-use" checker cannot process this.

#include <vector>

#include <string>

#include <cstring>

#if ENABLE_PLUGIN_LOADING

#if defined(_WIN32)

typedef PluginLibrary_Windows PluginLibrary_SysDep;

#else

typedef PluginLibrary_Unix PluginLibrary_SysDep;

#endif

struct loaded_plugin

{

  PluginLibrary_SysDep plugin_library_handle;

  struct heif_plugin_info* info = nullptr;

  int openCnt = 0;

};

static std::vector<loaded_plugin> sLoadedPlugins;

MAYBE_UNUSED heif_error error_dlopen{heif_error_Plugin_loading_error, heif_suberror_Plugin_loading_error, "Cannot open plugin (dlopen)."};

MAYBE_UNUSED heif_error error_plugin_not_loaded{heif_error_Plugin_loading_error, heif_suberror_Plugin_is_not_loaded, "Trying to remove a plugin that is not loaded."};

MAYBE_UNUSED heif_error error_cannot_read_plugin_directory{heif_error_Plugin_loading_error, heif_suberror_Cannot_read_plugin_directory, "Cannot read plugin directory."};

MAYBE_UNUSED static void unregister_plugin(const heif_plugin_info* info)

{

  switch (info->type) {

    case heif_plugin_type_encoder: {

      auto* encoder_plugin = static_cast<const heif_encoder_plugin*>(info->plugin);

      heif_unregister_encoder_plugin(encoder_plugin);

      break;

    }

    case heif_plugin_type_decoder: {

      // TODO

    }

  }

}

struct heif_error heif_load_plugin(const char* filename, struct heif_plugin_info const** out_plugin)

{

#if ENABLE_MULTITHREADING_SUPPORT

  std::lock_guard<std::recursive_mutex> lock(heif_init_mutex());

#endif

  PluginLibrary_SysDep plugin;

  auto err = plugin.load_from_file(filename);

  if (err.code) {

    return err;

  }

  heif_plugin_info* plugin_info = plugin.get_plugin_info();

  // --- check whether the plugin is already loaded

  // If yes, return pointer to existing plugin.

  for (auto& p : sLoadedPlugins) {

    if (p.plugin_library_handle == plugin) {

      if (out_plugin) {

        *out_plugin = p.info;

        p.openCnt++;

        return heif_error_ok;

      }

    }

  }

  loaded_plugin loadedPlugin;

  loadedPlugin.plugin_library_handle = plugin;

  loadedPlugin.openCnt = 1;

  loadedPlugin.info = plugin_info;

  sLoadedPlugins.push_back(loadedPlugin);

  *out_plugin = plugin_info;

  switch (loadedPlugin.info->type) {

    case heif_plugin_type_encoder: {

      auto* encoder_plugin = static_cast<const heif_encoder_plugin*>(plugin_info->plugin);

      struct heif_error err = heif_register_encoder_plugin(encoder_plugin);

      if (err.code) {

        return err;

      }

      break;

    }

    case heif_plugin_type_decoder: {

      auto* decoder_plugin = static_cast<const heif_decoder_plugin*>(plugin_info->plugin);

      struct heif_error err = heif_register_decoder_plugin(decoder_plugin);

      if (err.code) {

        return err;

      }

      break;

    }

  }

  return heif_error_ok;

}

struct heif_error heif_unload_plugin(const struct heif_plugin_info* plugin)

{

#if ENABLE_MULTITHREADING_SUPPORT

  std::lock_guard<std::recursive_mutex> lock(heif_init_mutex());

#endif

  for (size_t i = 0; i < sLoadedPlugins.size(); i++) {

    auto& p = sLoadedPlugins[i];

    if (p.info == plugin) {

      p.plugin_library_handle.release();

      p.openCnt--;

      if (p.openCnt == 0) {

        unregister_plugin(plugin);

        sLoadedPlugins[i] = sLoadedPlugins.back();

        sLoadedPlugins.pop_back();

      }

      return heif_error_ok;

    }

  }

  return error_plugin_not_loaded;

}

void heif_unload_all_plugins()

{

#if ENABLE_MULTITHREADING_SUPPORT

  std::lock_guard<std::recursive_mutex> lock(heif_init_mutex());

#endif

  for (auto& p : sLoadedPlugins) {

    unregister_plugin(p.info);

    for (int i = 0; i < p.openCnt; i++) {

      p.plugin_library_handle.release();

    }

  }

  sLoadedPlugins.clear();

}

struct heif_error heif_load_plugins(const char* directory,

                                    const struct heif_plugin_info** out_plugins,

                                    int* out_nPluginsLoaded,

                                    int output_array_size)

{

  auto libraryFiles = list_all_potential_plugins_in_directory(directory);

  int nPlugins = 0;

  for (const auto& filename : libraryFiles) {

    const struct heif_plugin_info* info = nullptr;

    auto err = heif_load_plugin(filename.c_str(), &info);

    if (err.code == 0) {

      if (out_plugins) {

        if (nPlugins == output_array_size) {

          break;

        }

        out_plugins[nPlugins] = info;

      }

      nPlugins++;

    }

  }

  if (nPlugins < output_array_size && out_plugins) {

    out_plugins[nPlugins] = nullptr;

  }

  if (out_nPluginsLoaded) {

    *out_nPluginsLoaded = nPlugins;

  }

  return heif_error_ok;

}

#else

static heif_error heif_error_plugins_unsupported{heif_error_Unsupported_feature, heif_suberror_Unspecified, "Plugins are not supported"};

struct heif_error heif_load_plugin(const char* filename, struct heif_plugin_info const** out_plugin)

{

  return heif_error_plugins_unsupported;

}

struct heif_error heif_unload_plugin(const struct heif_plugin_info* plugin)

{

  return heif_error_plugins_unsupported;

}

void heif_unload_all_plugins() {}

struct heif_error heif_load_plugins(const char* directory,

                                    const struct heif_plugin_info** out_plugins,

                                    int* out_nPluginsLoaded,

                                    int output_array_size)

{

  if (out_nPluginsLoaded) {

    *out_nPluginsLoaded = 0;

  }

  return heif_error_plugins_unsupported;

}

#endif

const char* const* heif_get_plugin_directories()

{

  auto plugin_paths = get_plugin_paths();

  size_t n = plugin_paths.size();

  auto out_paths = new char* [n + 1];

  for (size_t i = 0; i < n; i++) {

    out_paths[i] = new char[plugin_paths[i].size() + 1];

    strcpy(out_paths[i], plugin_paths[i].c_str());

  }

  out_paths[n] = nullptr;

  return out_paths;

}

void heif_free_plugin_directories(const char* const* paths)

{

  for (int i = 0; paths[i]; i++) {

    delete[] paths[i];

  }

  delete[] paths;

}